Just about to say the same thing.  This is in no way a safety issue.  The question is whether the entry is at a high point or not compared to previous years (or even eras).

I think it was on the Nostalgia forum that someone posted an entry list from the early 90s for the British championship - what was the equivalent of the BSB now.  Many of the riders were current or previous TT competitors.  My take on this is that the quality of the TT entry is dictated to very heavily by the quality of riders in other championships.  Imagine a scenario say in say ten years time where the BSB entry quality has fallen away, then it's likely that the quality of the TT entry would be impacted (and before anyone gets into a discussion how that that could never happen to BSB - this is a theoretical scenario!)

Currently then the TT organisers have a good crop of potential riders at their disposal.  It may not be so at some point in the future.  It may also get better of course!